At Lewis she will work on existing accounts and new business to help the agency deliver integrated campaigns internationally.
Lewis UK MD Giles Peddy said Jones’ hire came after a period of growth and new business wins. He said the agency was looking to build the team to support growth, both in the UK and globally.
He added that further hires at associate director level were expected.
Speed MD Kate Bosomworth said: "We’re delighted for Ruth after nine years with Speed and she will remain a good friend of the agency."
John Brown, director of Speed's consumer tech practice and digital offering, will now lead the the whole technology team.
Bosomworth added that the agency was on a strong recruitment drive and "looking to fill senior-level positions to support the tech team," but whether Jones’ position would be replaced directly would "depend on how the structure develops".
Jones’ departure follows that of Scott McLean, who was joint MD with Bosomworth before he left the agency at the end of September.